feat: #2260 Add explanation into README.md for Servant pattern (#2586)

* issue id: #2260
explanation: modify README.md file.
- add Explanation selection
- add Real-world example, under the Explanation selection. Example express the  the king, queen and servant relationship.
- add plain-word, wiki say
- add programmatic example with code of  king, queen and servant classes.
- add console output by running code at local.

* fix: #2260
- remove a line from readme.md

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Co-authored-by: Md Saiful Islam <md.saiful@revesoft.com>